Check if the flag is already set before setting it, and vice versa for clearing.
Obviously setting or clearing a flag twice isn't a problem on it's own, but it implies that there's an issue where some piece of code assumed an opposite state of the flag. Signed-off-by: Sasha Levin <[email protected]> --- include/linux/page-flags.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d1fe1a7..36b0bef 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -130,6 +130,12 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H +#ifdef CONFIG_DEBUG_VM_PAGE_FLAGS +#define VM_ASSERT_FLAG(assert, page) VM_BUG_ON_PAGE(assert, page) +#else +#define VM_ASSERT_FLAG(assert, page) do { } while (0) +#endif + /* * Macros to create function definitions for page flags */ @@ -139,11 +145,13 @@ static inline int Page##uname(const struct page *page) \ #define SETPAGEFLAG(uname, lname) \ static inline void SetPage##uname(struct page *page) \ - { set_bit(PG_##lname, &page->flags); } + { VM_ASSERT_FLAG(Page##uname(page), page); \ + set_bit(PG_##lname, &page->flags); } #define CLEARPAGEFLAG(uname, lname) \ static inline void ClearPage##uname(struct page *page) \ - { clear_bit(PG_##lname, &page->flags); } + { VM_ASSERT_FLAG(!Page##uname(page), page); \ + clear_bit(PG_##lname, &page->flags); } #define __SETPAGEFLAG(uname, lname) \ static inline void __SetPage##uname(struct page *page) \ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
